In some applications in the use of power tools the handling of fastener such as screws is particularly cumbersome. This is especially true for the handling of small screws. For these applications a so called vacuum adapter may be used. The vacuum adapter is an auxiliary device that is adapted to be arranged at the front end of a power tool so as to house the tool bit that is arranged to interact with the fastener to be fastened.
The idea of the vacuum adapter is to suck up a fastener, e.g. a screw, screw head first, such that the screw head will be sucked into the vacuum adapter and into contact with the bit. Subsequently the power tool will be relocated such that the fastener will be positioned at the hole into which it is to be screwed such that the tightening operation may be initiated.
One type of such vacuum adapter is disclosed in U.S. Pat. No. 3,786,845. The vacuum adapter includes a hollow portion in which a negative pressure is produced. A front part of the vacuum adapter is telescopically arranged with respect to a main part. This telescopically arranged portion allows the screwdriver bit to be continuously repositioned between a distal and a proximal position with respect to a screw conduit into which a screw is meant to be sucked by means of the negative pressure inside the hollow portion.
There are however problems involved with this and other vacuum adapters. A first problem is that the bit may be prematurely worn out. This problem arises inter alia since an important part of the tightening operations performed by the power tool will be initiated before the bit is correctly located inside the recess of the fastener head. As the tightening operation proceeds the bit will normally find its way into the recessed fastener head.
However, an incorrectly located fastener will in most occasions lead to wear of both the recess of fastener head and the bit in the initial phase of the operation before the bit has found its way into the recess of the fastener head. Further, as the bit will be continuously worn the contact to each new fastener will gradually worsen, whereby the wear of the fastener heads may be more severe. Also, the control of the tightening operation will be negatively affected and it may not be possible to control the torque by which the screw is fastened to a satisfactory degree.
Another problem related to vacuum adapters is that the front part of them needs to be individually adapted to a specific type of fastener. Typically, both the length and the diameter of the screw conduit are adapted to a specific type of fastener. For a fastener of another length or a differently sized fastener head the vacuum adapter needs to be replaced by a vacuum adapter with a screw conduit of another size. It is generally considered to be too cumbersome to exchange the vacuum adapter. Therefore, in general industrial applications different tools are used with different types of fasteners.
Hence, there is a need of a vacuum adapter that reduces the problems discussed above.